The present invention relates to a method of making a cooling jacket for an electrical machine such as an electric motor or generator.
Electric motors and generators, such as a brushless permanent magnet motor, generate considerable heat and must include a cooling system. U.S. Pat. No. 5,859,482, issued 12 Jan. 1999 to Crowell et al., describes a cooling system wherein a cooling fluid is circulated through a cooling jacket which engages and conducts heat away from the stator of the machine. The cooling jacket includes a stator frame which is cast around cooling conduits. Another cooling jacket assembly for cooling an electric motor or generator is described in U.S. Pat. No. 6,300,693, issued 9 Oct. 2001 to Poag et al. U.S. Pat. No. 4,516,044 describes an electric motor heat exchange apparatus wherein cooling passages are formed in an internal surface of a hollow cylindrical housing. It is also known to drill axially extending cooling passages in a motor housing. These prior systems are expensive or difficult to manufacture, or have other disadvantages.